Color television system



1366- 1934. A. McL. NICOLSON COLOR TELEVISION SYSTEM Filed Feb. 11, 1951I! m mmmu wmaq 3 8 1| o um I UN v M HWH |NVENTOR AlaxandEI M LBanNiculsun MM I? W ATTORNEY natural colors.

' Patented Dec. 25,1934

' PATENT OFFICE 1,985,685; COLOR TELEVISION SYSTEM I Alexander McLeanNicolson, New York N. Y assignor to Communication Patents, Inc., NewYork, N. Y., a corporation of Delaware Application February 11, 1931,Serial No. 514,926

11 Claim.

This invention relates to the art of electrooptical transmissionsystems, and particularly to the transmission of electro-optical imagesin colors.

An object of the invention is to transmit images of objects in colors.

Another object of the invention is to transmit and receiveelectro-optically colored images of objects in a simplified and economicmanner.

A further object of the invention is to receive images of objectselectro-optically in colors using three color channels to obtain thecolored image for observation.

It has been disclosed in my copending application Serial Number 450,630,filed May 8, 1930, now Patent No. 1,901,116, granted March 14, 1933, how

' to transmit images of objects electrically in their One embodiment ofthis colored television system utilizes a color scanning arc with areceiving are so constructed that the color is imparted directly to thearc itself, which may be observed directly, or on a screen on which thearc is projected. Other television systems are well known in whichcolors are presented directly on the receiving screen, color beingimparted to each unit area. a

In the present invention an outstanding feature of the colortransmission system is the manner in which the scanned image obtains itscolor, while at the same time obtaining exceptional definition anddetail. The present invention contemplates utilizing selectivephotoelectric cells through intrinsic properties or associate colorfilters at the transmitter and colored lamps at the receiving position.This portion of the apparatus is in addition to the black and whitescanning at the receiver. For instance, a transmitting lightscanner isemployed in the usual way, color selectivity being obtained by theselectivity of a plurality of sensitive photo cells. The reception ofthe three colors on corresponding colored projecting lamps issupplemented by complementary black and white scanning.

Another feature of importance in the present system is that the methodof obtaining color at the receiver may' be independent of thetransmitter, and furthermore, the application of the color aids inobtaining detail not actually represented by varying degrees of currentintensity.

be a direct connection, or may be the usual type of carrier channeltransmission system well known in the art. That is, each colored elementof the transmitter may be directly connected with its correspondingelement at the receiver through its own particular wire circuit, or thiswire circuit may be replaced by a carrier frequency circuit, eachchannel having its individual carrier frequency.

The invention will be more comprehensible from the following descriptiontaken in conjunction with the accompanying drawing, in which:

Fig. 1 shows diagrammatically a transmission system; and

Fig. 2 shows the conjugate receiving system.

In Fig. 1 an object represented by the arrow 5 is explored by a ray orlight projected from the scanning screen 6 through the pinhole 7 ofcamera 8. The are screen 6 may be supplied from a supply apparatus 10 inaccordance with the systems disclosed in several of my copendingapplications, particularly Ser. No. 397,826, filed October 7, 1928 nowPatent No. 1,863,278, issued June 14, 1932. In brief, this supplyapparatus may comprise an arc potential and a field supply to propagatethe are over the electrode rails in the screen. An output line 11 isshown for transmitting to the receiver synchronizing impulses tomaintain the transmitting and receiving arcs in synchronism, the detailsof which are disclosed in the above mentioned application. It is to beunderstood at this point that any scanning system known in the art whichemploys an exploring ray may be substituted for the system justdescribed, without departing from the fundamental principles of theinvention.

In the present system three photoelectric cells 14, 15 and 16 are madeselective to the colors blue, green and red, by appropriate colorfilters 18, 19 and 20, respectively. These cells operate in the usualway, that is, the cell 14 receives blue light reflected from the object5 when the unit area explored has the color blue; the cell 15 isactuated by light reflected from a unit area having a green color; andlikewise the cell 16 is actuated by light reflected from a unit areahaving a red color. The amplitude of the current generated in thesecells will depend, of course, upon the amount of the respective colorpresent in the unit area from which the light is reflected. Forinstance, each cell may receive equal intensities of light according tothe colorization of the unit area which contains the three colors inequal proportions, or, in case theunit area is white, each cell is ad-.iusted to generate equal voltages. These cells may be intrinsicallyselective to the colors named or other colors, as well as being madeselective by the filters.

The cells are shown having individual output terminals 23, 24 and 25,another terminal 26 being common to all of the cells. The output of 4.supply apparatus 10 and amplifying apparatus 28 to the transmittermodulator 30 are shown dotted to indicate that these circuits may becontinued as such to the receiving apparatus or may be associated withthe carrier frequency apparatus shown.

Referring to Fig. 2, which shows the receiving system, an antenna 35 orwire line 36 impresses the received currents on a receiver 37 followedby a demodulator receiver 38. From the receiver demodulator an outputcircuit 40 and conductors 41, 42, 43 and 44 transmit the impulses forsynchronizing supply apparatus 46 with the transmitter apparatus 10 andthe impulses of the individual color signals, respectively, these conductors corresponding with conductors ll, 23, 24, 25 and 26 of Fig. 1.These conductors just mentioned in Fig. 2 are shown partially dotted, toindicate that the apparatus to the right thereof in Fig. 2 may bedirectly connected to the apparatus shown to the left of the dottedportion of the conductors of Fig. 1.

The supply apparatus 46 feeds and controls the scanning arc on a screen47, which projects light through a pinhole 48 in a camera 49 to anobservation screen 50. The are receives impulses for changing itsintensity through a four winding input transformer 52 having threeprimaries 53, 54 and 55. In these color circuits are also lamps 57, 58and 59, in series with the primary windings just recited. Each lamp hasa respective color filter 61, 62 and 63 designated as red, green andblue and correspond, respectively, with color filters 20, 19 and 18 ofFig. 1.

Each of the lamps entirely flood the screen 50 whenever energized, withlight passing through their respective filters. That is, uponenergizetion of the lamp 57 the screen 50 will be flooded with redlight; upon energization of the lamp 58 the screen 50 will be floodedwith green light; and upon energization of the lamp 59, the screen 50will be flooded with blue light. An energy supply 64 permits varying thecolor level on the screen, each lamp being individually energized at anytime and in any amount.

To operate the above described apparatus as a color televisiontransmission and receiving system, the arc screen 6 scans the object 5with white light. The cells 14, 15 and 16 receive light in accordancewith the color pattern of the object 5 through their respective filters,and produce in their respective circuits currents of varying amplitudein accordance with vthe intensity of the colors, These currents aretransmitted through the apparatus shown or directly to the receivingsystem to the right of the dotted conductors in Fig. 2.

Assuming that the red cell 16 is energized, this impulsefwill beimpressed upon the are 42 and produce a bright spot of light at aparticular the red color on the rest of the screen will not,

interfere with the reproduced image being observed by the eye. Shouldthe next impulse be characterized by a green color, this impulse willproduce a bright spot of light by being transmitted-through the primarywinding 54 to the' arc screen 4'7, producing at another position on thescreen 50 a bright spot of light. Simultaneously therewith, the lamp 58will be energized and thescreen 50 will receive green light, the spot orunit area being defined by its illumination from the arc 4'1 and the eyebeing conscious of the green color by the general illumination.Similarly, a blue element on the object 5 will be received as blue onthe screen 50 by the simultaneous projection thereonpf the blue floodlight and the illumination of the unit area. Should a unit area onobject 5 be white, all three cells will send equal impulses, and thesimultaneous projection of red, green and blue on the screen 50 willproduce a white light area. Shades of the various colors will betransmitted in their true relationship by the varying voltage impulsesgenerated by the selective cells at the transmitter, the receiving lampsprojecting on the screen 50 a proportionate amount of color.

It is to be noted in this invention that should a colorscheme beparticularly mottled, that is, have I a great many colors alternatingtherein, then by the rapid repetition of the red, green and blue colorsupon common areas, a nil effect as far as color is concerned will beproduced. If any predominant color is desired in a picture, it may beobtained by adjusting the local energizat'ion of the lamps 57, 58 and 59from the local source 64. For instance, if a red glow illuminates thescreen continuously, this red tint will be given to the screen bytinting the unit areas without losing definition. Such effect may bedesired in the case of fire or fire scenes similar to the productionthereof by colored film in the motion picture art. It is possible,therefore, to regulate the color reception to any desired degree byemphasizing any one of the color channels under manual control.

The receiving apparatus is also ,applicable to non-color transmissions,whereby color is imparted to the received image. For instance, the lamps57, 58 and 59 may be adjusted to provide unequal illumination for equalreceived current impulses, in whichcase the received image will besuffused with a predominant color.

Itis obvious that other systems embodying the principle of the inventionreadily suggest themselves, these systems being defined by the appendedclaims.

What is claimed is: 1. In an electro-optical transmission system, anexploring ray of light, means for detecting different colors of unitareas of an object, means for transmitting said light characterizationsto a receiving point, means for producing an image of an object at saidreceiving point, and means at said receiving point for flooding aninstantaneous field of view with colored light corresponding to the unitarea scanned.

2. In an electro-optical transmission system,

"means for obtaining varying light characterizations according to thecolor of an object scanned, means for segregating each individual colorimpulse to a particular channel, means for connecting said channels withscanning apparatus at a receiving point, said receiving apparatusproducing an image of said object, and means at said receiving point forcharacterizing an entire field of view observable at all times withcolor in accordance with the particular color received.

3. In an electro-optical transmission system, an object whose image isto be transmitted, means for detecting varying light and shade densitieson said object in accordance with the color thereof, means for obtainingvoltage characteristics corresponding to said light and shade'densitiesin separate circuits, means for transmitting said individual colorcharacterizations to receiving apparatus, said apparatus producing animage of said object, an observation screen observable at all times, andmeans included in said receiving apparatus for coloring all of saidobservation screen with color in accordance with the currents in eachindividunit area scanned at said transmitter, said entire field of viewbeing observable at any instant.

5. An electro-optical transmission system for television and the like,an object whose image is to be transmitted, a plurality of means forgenerating currents in accordance with the light and shade densities ofthe object, said means being of said observation screen with light inaccord-' ance with the color otgthe unit area of the obiec scanned atany particular instant.

6. In a receiving system for television, a plurality of separatechannels'for transmitting currents characterized by colors of unit areasof the transmitted object, a receiving screen, means for producing ascanning ray of light across said screen varying in intensity inaccordance with the light and shade density 01' the colors thetransmitted object, and means for illuminating all of said screen withlight colored in accordance with the color of a unit area of the objectat any particular instant.

7. In a receiving system for colored television, a receiving screencharacterized by light intensities corresponding to light and shadedensities of the image of a transmitted object, individual colorprojectors for illuminating said observation screen connected toindividual color transmission channels from a transmitter, and meanscommon to said individual channels for scanning said observation screen,said common means being actuated by all impulses received while saidindividual means are actuated in accordance with the color of thetransmitted image of the object.

8. The method of color transmission electrooptically comprising scanningan object with light, obtaining current variations corresponding withlight and shade intensities of the object in accordance with the colorof unit areas thereof, each color having an individual channel,reproducing an image of said object, and simultaneously flooding allunit areas of an observation screen with color in accordance with thecolor oi. the unit area at that instant, all of said unit areas beingobservable at any instant.

9. The method of receiving colored images comprising receiving impulsescharacterized by the light and shade intensities of unit areas of anobject, reproducing an image from said impulses, and observablyimparting to all unit areas the colors of each unit area in accordancewith the amplitude 01 the impulses received.

10. In an electro-optical transmission system, means for creatingcurrents characterized by the light and shade densities of an object,means for receiving said currents on receiving apparatus, means forproducing an image from said currents in black and white contrast oflight at said receiving point, and means using said currents forcharacterizing all unit areas of said received image with the color ofeach unit area.

11. In an eleotro-optical transmission system for color television,means for scanning an object with light in unit areas, means forproducing electrical currents proportional to the intensity of thecolors in said object, means for segregating each of said impulsescharacterized by a specific color, means for transmitting said impulsesto a receiving apparatus while main tai'ning their segregation, meansfor scanning an observation screen with white light corresponding to theimpulses in all of said colored channels, means for synchronizing saidscanning apparatus, and means for illuminating all of said observationscreen with colors particularizedby the impulses in the channelscorresponding to

